1. Field of the Invention
The present invention relates generally to the field of wheelchairs and, more specifically, to a manual braking system with a variable braking force and quick release, detachable wheels for manual wheelchairs.
2. Description of the Related Prior Arts
Numerous types of braking mechanisms for manual wheelchairs are known in the art. The most typical manual wheelchair brake is a manual “over center” locking device which is activated by a lever arm and, when forced into its locking position, presses a braking member against the surface of the wheelchair tire creating a frictional braking action. Several factors mitigate against the usefulness and reliability of these types of brakes. Loss of tire pressure reduces the frictional force exerted by the crossbar on the tire and hence reduces the braking effect. A significant air pressure loss leaves these brakes useless. During transfer in and out of the chair, this type of brake allows the tire to slide underneath the crossbar and the wheelchair to move. Similarly, the brakes are ineffective and will not adequately hold the wheelchair on an incline. Other types of manual brakes include caliper type brakes manually activated with a lever arm mounted to a cable and brake assembly causing brake pads to press against the rim of the wheelchair wheel. Typically, braking mechanisms for wheelchairs only apply a braking force to one wheel. If an equal braking force is desired on both wheels, the user is required to perform the difficult task of using both arms at the same time. Finally, these types of manual brakes, whether caliper type brake or not, do not allow for a variable braking force to be exerted on the tire or rim. A variable braking force allows the user to both slow the wheelchair and ultimately stop it and hold it in place when desired.
Patents to Ross and Gunther, U.S. Pat. No. 5,358,266 and Lautzenhiber, U.S. Pat. No. 4,805,711 describe a braking member, which applies a braking frictional force directly to the wheelchair tire which is manually activated by a lever arm. There are also disclosed in the art several manual braking mechanisms which utilize a cable actuated caliper braking mechanism on the rim of one wheel or on the rims of both wheels with two distinct braking systems operating separately. Examples of these types of braking mechanisms are disclosed in patents to Herron, U.S. Pat. No. 4,560,181; Kawecki, U.S. Pat. No. 4,204,588; and Lemarie, U.S. Pat. No. 4,538,826. Finally, a patent to Berry, U.S. Pat. No. 5,492,355 discloses a caliper type braking mechanisms that discloses caliper type brakes which operate on the tire rim of each wheelchair wheel and can be activated by the use on one lever. Many of the same deficiencies discussed above apply to each of these braking mechanisms.
Wheelchair users have reason to frequently remove the wheels from their wheelchairs. It is often done for storage purposes, for brake adjustment, for wheel repair, and for wheel exchange. For example, in order to store a wheelchair in a vehicle, it is often desirable to remove the wheels.
Heretofore, the wheels on manual wheelchairs and other types of wheelchairs have been attached to the wheelchair frame by some type of hub with the wheels secured to the hub with nuts and bolts. In order to remove the wheels from the wheelchair, it has been necessary to unscrew and remove each of the nuts and bolts securing the wheel to the hub. This is a time consuming and cumbersome process. Once again, wheelchair users who have arm or hand limitations may not be physically able to remove the nuts and bolts.
More recently, it has become common in the art to attach wheels to manual wheelchairs using quick release locking pins which hold the wheel to the axle. In this type of design, it is difficult to also have a braking means on the wheelchair wheel other than the manual “over center” locking device which presses a braking member against the surface of the tire as described herein. Heretofore, other braking systems such as those which utilize caliper type brakes operating on the rim of the wheelchair wheel, have been ineffective on wheelchairs with quick release locking pins because the braking means had to be released and moved or disassembled in order to remove the wheel and thereby defeating the purpose of the quick release locking pin.
It is desirable to have a wheelchair with an effective easily operatable manual braking mechanism and, at the same time having quick release detachable wheels.